Flash plug



J. FREDETTE April 16, 1935.

FLASH PLUG Filed Oct. 7, 1932 Patented Apr. 16, 1935 FFEQ FLASH Josephat Fredette,

PLUG

St. Jean Baptiste,

Manitoba, Canada Application October 7, 1932, SerialNo. 636,673 InCanada August 29, 1932 1 Claim.

The invention relates to improvements in flash plugs and an object ofthe invention is to provide an improved plug of simple design which canbe manufactured at comparatively small cost and having the parts alldesigned so that they can be easily and quickly assembled in the wellknown manner.

A further object of the invention is to provide a plug having astationary exposed electrode and a slotted receptacle enclosing the sameand con-- taining a spherical ball freely movable in the receptacle andoperating to maintain the parts free of deposit and accordingly clean.

A still further object is to construct the receptacle so that thecompressed charge can pass freely and directly into the receptacle andbe effectively distributed over the entire cross sectional area thereofand further such that the ball when riding the bottom of the receptacleor engaged with the sides thereof, will be at a constant distance fromthe stationary electrode, thereby maintaining a constant gap in allpositions of the ball.

A still further object of the invention is to construct the bottom ofthe receptacle on which the ball rides so that it offers a minimumresistance to the shifting of the ball in any direction, sucharrangement insuring that the parts will be maintained clean or freefrom deposit due to the continuous rolling movement of the ball.

A further object is to provide the receptacle with a fiat bottom onwhich the ball rides and the electrode with an exposed end parallelthereto, such resulting in the maintaining of the ball at a constantdistance from the electrode as it shifts within the receptacle, it beingunderstood that the sides of the receptacle limit the side movement ofthe ball in respect to the electrode.

A further object of the invention is to provide 40 a plug which willgive in all positions of the ball within the receptacle a relativelylarge evenly distributed flash when the plug is in use, the flashactually when under observation, having the appearance of an annularilluminated ring around the ball.

With the above more important objects in view, the invention consistsessentially in the arrangement and construction of parts hereinaftermore particularly described, reference being had to the accompanyingdrawing, in which:--

Fig. l is a side view of the plug.

Fig. 2 is an enlarged detailed vertical sectional view at 22 Figure 1.

Fig. 3 is a vertical cross sectional view at 33 (or. 123-169) C Figure 2and showing the ball in a changed position.

4 is a horizontal cross sectional view at 3-3, Figure 2 and showing theball in a changed position.

In the drawing like characters of reference indicate corresponding partsin the several figures.

The central stem l of the plug has the upper end thereof screw threadedto receive the customary terminal nut 2 directly under which is locateda metal washer 3 which rests on the upper end of the porcelain insulator4. It will be observed that the lower end of the stem terminates in anenlarged head 5 which is seated or countersunk in the lower end of theinsulator and which forms an exposed central electrode. The porcelaininsulator is of the usual shape and presents a bulbous portion 6.

A metallic shell 1 is supplied and the shell has the lower endexternally screw threaded as indicated at 8 and the upper endinternally, screw threaded as indicated at 9 and it is supplied with aninternal tapering seat Ill adapted to support the bulbous portion of theporcelain. A gas proof packing l l is interposed between the seat andthe 20 porcelain as shown and the upper end of the shell receives ascrew threaded bushing l2 and between the bushing and the bulbousportion of the insulator, a second gas proof packing is is inserted.

The above parts with the exception of the 30 specific construction ofthe lower end of the stem, are well known so a detailed description ofthe same is not herein given, it being sufficient for the purpose of thepresent disclosure to understand that the inserted porcelain is heldfirmly 3 in place between the seat of the shell and the bushing when thebushing is screwed down, the packings insuring at such time of gas tightjoints.

The lower end of the shell is formed to provide an integral ballreceptacle it having a plurality of cross slots l5 therein. Actually thereceptacle is initially in the form of a cylinder having a closed bottomand the cylinder and bottom are subsequently cross out vertically suchas by a saw to provide the slots which are preferably equispaced andpass across the bottom of the recep tacle and up the side walls thereof.

Within the receptacle, I locate a metallic ball l6 forming a movableelectrode, such ball having a predetermined selected diameter.

It will be particularly noted that the inner face of the receptaclebottom is horizontal or flat and that the exposed face of the electrode5 is parallel thereto with the result that the gap between 2 the balland the electrode 5 is maintained constant irrespective of the positionof the ball when riding the receptacle. Attention is here directed toFigure 3 where the ball is at the side of the receptacle and in thisfigure, it will be observed that the side wall or" the receptacle hasstopped the ball with its uppermost point directly underlying theperipheral edge of the electrode 5 so that in all side positions of theball, the gap is the same as in the central or any intermediateposition.

The relative arrangement of the electrode 5, the ball and thereceptacle, not only provide a plug which will maintain a constant sparkgap but the flat inner face of the receptacle has the further verydesirable advantage that it ofiers a minimum resistance to the shiftingof the ball when the plug is in use with the result that the ball ispractically continuously in movement and accordingly very effectivelymaintains the associated parts free of deposit or clean. It will bereadily seen that if the plug is tilted in any direction from thevertical, the ball will immediately roll to the low side and in actualpractice,

plug is being shifted to cause the almost continuous rolling of theball.

It will also be observed that the shape of the receptacle is such thatwhen the plug is in use, the compressed firing charge will be passed directly into the receptacle through the slots and distributed evenlythroughout the entire cross sectional area of the interior of thereceptacle.

I may say that I have made plugs as herein disclosed and have placedthem under observation and I find that in all positions of the ball,there is an annular flash surrounding the ball which is quite distinctto a spark at a single point. I

What I claim as my invention is:--

In a flash plug, a substantially cylindrical metallic shell having thelower end thereof closed by a fiat lying bottom and forming a receptacleat the lower end of the shell and having the bottom and side walls ofthe receptacle cross slotted at spaced intervals, a ball normally ridingthe bottom of the receptacle and forming one electrode, an insulatingmember mounted in the shell and overlying the receptacle and a secondelectrode in the form of a circular stem extending cent-rally throughthe insulating member and carried by the insulating member andterminating in an enlarged circular area presenting a face exposed tothe receptacle and parallel to the bottom of the receptacle, thedistance between the latter face and the bottom of the receptacle beinggreater than the diameter of the ball whereby a gap is reserved betweenthe top of the ball and said exposed face.

JOSEPHAT FREDET'IE.

